Chilean Miners: Surviving the Darkness

Find out what supplies rescuers are squeezing through a 3.19-inch hole.

The plight of the 33 miners trapped in northern Chile since Aug. 5 is harrowing enough. To survive, they must endure constant 90 percent humidity, avoid starvation, battle thirst, guard against fungus and bacteria, and stay sane enough to safely do the work necessary to aid their own rescue. Yet even if they accomplish all that, they face another danger: the constant darkness.

Decades of research has shown the human body is built to function on the rhythm of the rising and setting sun. If sunlight doesn't tell our brains when we should be asleep—and if we don't eat, exercise, and sleep on a fairly regular daily schedule—humans can develop all sorts of health problems over time, from irregular metabolism to heart disease to deficiencies of key vitamins. Disruptions to our body's 24-hour clock can impair motor skills (proof: doctors who toil over long shifts are far more likely to get in car accidents). They can make us irritable or depressed. To feel the effects of those disruptions each day would be like trying to live life in a constant state of jet lag.

All of this is bad news for doctors trying to care for the men trapped 2,230 feet underground. To be sure, some of the potential problems for the men have easy fixes: a 3.19-inch-wide supply line provides them with food, water, and nutritional supplements such as vitamin D, which can replace the nutrients they are not getting from sunlight. But the physical and psychological toll of the darkness is harder to combat. A tired miner could sink slowly into depression, leading to debilitating emotional issues before or after he returns to the surface. He could make a mistake as the group works to build the bottom part of its rescue shaft, injuring himself or another miner at a time when none of them has access to emergency medical care. A miner already at risk for diabetes could develop it if he lacks a daily eating and exercise routine. All these risks only grow with time, and it may be December before engineers finish drilling the rescue hole.

One way to keep the miners on a daily routine is to simulate light and dark periods during each day. The men have already designated light and dark areas in the roughly half-mile-long tunnel where they are living, but the battery-powered lamps in the lighted areas may not be bright enough to trick the men's internal clocks into thinking it's daytime. "If you have really dim light, you can still read a newspaper, but that's not enough to synchronize a 24-hour clock," says Charles A. Czeisler, who directs the sleep medicine division at Harvard Medical School. (This situation could improve soon: this past weekend, rescuers successfully installed an electrical wire down one of the supply holes, and an American company called Lighting Science Group Corp. says it expects to have custom-designed LED lights on the way to Chile by week's end.)

The good news for the miners is that the circadian system, the brain-based signals that keep the body in rhythm, can do its job without sunlight. Night-shift workers have an elevated risk of some health problems not because they work nights, but because they work nights and then flip-flop their schedules on the weekends, disorienting their internal clocks. "The shift worker is constantly shifting, even if he works his whole life," says Fred W. Turek, director of the Center for Sleep & Circadian Biology at Northwestern University. "The key is to maintain that 24-hour organization."

Chilean authorities, aware of these risks, have made the miners' daily routine a priority. Each miner has daily jobs to do. Several of them, working in 24-hour shifts, must be manning the tiny supply line. In the coming weeks, they will need to clear rock that falls as drillers on the surface carve out a rescue shaft. The miners also will have other responsibilities: one trapped man with medical training, for example, interviews all the others once per day about their skin, bowel movements, and other health indicators. He relays the reports "topside" via a telephone line or notes hauled up to the surface. The responsibility "actually gives him purpose down there," says Michael Duncan, NASA's deputy chief medical officer, who visited Chile to advise local authorities on the rescue. "He's really enjoying the role."

Rescuers at the surface are also helping miners pass the time during the hours they are scheduled to be awake. A fiber-optic projector, connected to a wire from one of three supply holes reaching the miners, can show movies and football matches in a 50-inch picture on the cave wall. The miners have received magazines (including a special edition of Chile's Que Pasa that featured their plight), Bibles, short stories, and journals. Rescuers are planning for them to produce performances for their families using a small video camera. The miners even got an iPod (sent to the surface for occasional recharging), but with speakers instead of headphones, so as to encourage communal use. In sum, almost anything goes in the effort to keep them entertained and engaged.

The challenge, of course, is ensuring that all 33 trapped men follow these protocols. "The regularity of when they get light and when they don't is critical," Czeisler says. "If they're waking each other up, [saying] 'You're scheduled to sleep right now but forget that, come have a meal now,' " then they risk the physical and emotional problems associated with a disrupted circadian clock. Jaime Manalich, Chile's health minister, has been monitoring the rescue from the beginning and said recently that the miners' mood was "surprisingly good." But he acknowledges that their excitement about making contact with the surface on Aug. 23 could soon subside. "These tough guys have to depend on (the surface supply line) even to drink water, therefore some of them have complained."

Manalich says the authorities are prepared on several fronts for what one might call the "depression phase" of the miners' experience. Rescuers have asked the men to divide into 11 groups of three in an effort to ensure each miner has people looking out for his safety. Shifts of psychiatrists are on duty at the surface, available for video chats at any hour. Antidepressants are on site, and Manalich says doctors will prescribe them if they feel it's necessary.

For their part, the miners have asked for other antidotes to their troubles. After recently installing a new air compressor to improve ventilation in the mine, rescuers allowed the men to share two packs of cigarettes per day. The miners have also requested red wine to celebrate Chile's Independence Day on Sept. 18. Will they get it? "We'll have to see how they behave," Manalich says.

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